Going from the point where you entered this particular hub go to the right.After a small piece you'll find a small uphill path on your right-turn up there to reach the save pool.It should be somewhere between 2 of the level portals.

As for beating Ghastly Gus-what you have to do is make a downward strike to hit his toes-2 hits will stun him,setting him up for a swipe with the sword.Once you do hit him once run away from him a piece to make him walk after you-this is when you should go for the downward strike.